Spinning, twisting or doubling machines have been provided heretofore with individual ring assemblies each comprising an annular ring holder on the ring rail of a spinning, doubling or twisting frame. The assembly includes an annular spinning, doubling or twisting ring which can rotate relative to the holder, being suspended or supported thereon by a pneumatic cushion. A traveler engaged by the yarn is designed to orbit around the upper rim of this ring.
Assemblies of this type are described, for example, in U.S. Pat. No. 3,324,643, British Pat. No. 1,000,365, German Federal Republic Open Application (Offenlegungsschrift) DT-OS 24 09 146, and German Democratic Republic patent No. 40 910.
A ring spinning machine or doubling machine which is in operation and has spinning rings which are rotatably supported on pneumatic cushions and are set in rotation by ring travelers can admit compressed air into the bearing gaps between the spinning rings and their support bearings in the ring frame when the spinning rings are stationary to produce an air cushion adapted to support the spinning rings. The admission of compressed air is interrupted if the spinning rings, adapted to displace air, are themselves able to draw in the air required for maintaining the air cushion after reaching a minimum rotational speed.
The starting of the spinning ring is performed aerostatically in such so-called hybrid bearings, i.e. by the admission of compressed air and building up an air cushion which supports the spinning.
To this end a compressed-air supply line, connected by means of a control valve to a source of compressed air and with branch lines extending in to the air gaps of all spinning rings, extends along the ring frame.
Immediately prior to starting the entire machine and by opening of the central valve all spinning rings are biased with compressed air and are able to start. The spinning ring is then aerodynamically operated after it has reached a specific minimum rotational speed at which it is able itself to draw in its bearing air and the supply of compressed air can be restricted or completely shut off by closing of the valve.
The spinning ring is set into rotation by means of the traveler which is entrained by the spindle through the thread or yarn. The drive of the spinning ring is therefore conditional upon the presence of the thread.
Accordingly, the spinning ring comes to a stop if the thread breaks and must be restarted after the thread break is remedied, i.e. the ends are tied. However, since the entire machine will then be in normal operation and the supply of compressed air will be shut down, restarting is not readily possible.